Q: Sometimes the cursor disappears from the screen of my five-year-old MacBook Air laptop. If I open and close the "lid" of the laptop, the cursor eventually reappears. What's wrong? Does it indicate that more serious problems are about to occur?

GENE MISKOWIEC, Little Canada

A: The disappearing cursor problem is common on Macs, and usually isn't serious. But there are several potential causes, and you'll have to figure out through trial and error which one is the source of your problem. Here are some of the common causes:

You may not have enough RAM memory available because of the way you use the Mac. RAM (random access memory) chips temporarily store data for software that's currently running. But you can use up your RAM storage capacity if you run too many Web browsers or other apps at the same time, or if you use two or more computer screens at once.
An app may be interfering with the cursor. To find the culprit, "force quit" apps one at a time.
Your Mac may have malware; run the free version of Malwarebytes (tinyurl.com/4sbj2pah).
If you use a wireless mouse, its battery charge may be low.
If you've recently installed a new operating system, you may need new Mac software drivers for a wireless mouse (see tinyurl.com/5n9426s2) or new mouse "firmware" (software for a particular device) from the manufacturer's website.
If you watch YouTube videos while using other apps, the video may be causing the cursor to disappear. This is by design; the cursor isn't supposed to be visible while a video is playing.

(For details about disappearing cursor causes and fixes, see tinyurl.com/bdcvvfdn or tinyurl.com/bde3rp7h or tinyurl.com/yv7xzupn).

Q: Comcast e-mail has gradually stopped delivering newsletters I subscribe to from the New York Times, clothing retailers Uniqlo and & Other Stories, the Minnesota Orchestra, the British newspaper Daily Telegraph, the activist Environmental Working Group, the Associated Press and others. I later learned those e-mails had been misclassified as spam and sent to the spam folder — although I can't find them there. I tried your advice about disabling the Comcast spam filter (see tinyurl.com/yckvt3xh), but it didn't help. I also didn't get any help from Comcast's technical support people. Do I need to get a new e-mail provider?

ALEXANDRA LIVINGSTON, St. Paul

A: Because spam is sent out in vast quantities every day (a process called bulk mailing), e-mail spam filters are designed to scrutinize all bulk mail, including newsletters. As a result, legitimate newsletters are sometimes misclassified as spam.

If that happens to you, you should be able to go into your Comcast spam folder, reclassify your newsletters as "not spam" and have them delivered to your inbox in the future. But you face two obstacles: Comcast's spam filter has a history of misclassifying too many legitimate e-mails as spam. In addition, anything that's classified as spam is deleted from your spam folder in seven days. As a result, you need to look in your spam folder every day or you could lose an e-mail that you really want.

If you don't want to put up with that, try using a free e-mail account from Microsoft's Outlook.com, Google's Gmail or Yahoo Mail.

E-mail tech questions to steve.j.alexander@gmail.com or write to Tech Q&A, 650 3rd Av. S., Suite #1300, Minneapolis, MN 55488. Include name, city and telephone number.